Didier Stevens

Sunday 27 November 2016

Update: xor-kpa.py Version 0.0.4

Filed under: Encryption,My Software,Update — Didier Stevens @ 0:00

This new version of xor-kpa adds the option -x to encode/decode, and also prints the hexadecimal value of the found keys.

xor-kpa_V0_0_4.zip (https)
MD5: FCE75B6125104D8AFC56A67B65FF75C0
SHA256: 3DCCA479D4C8CAC9B248B24F799184A69D0F10403593CB002248DD35CCE60FD4

Tuesday 22 November 2016

Simple Ciphers: cipher-tool.py

Filed under: Encryption,My Software — Didier Stevens @ 0:00

When I left my last position, my friends and colleagues with whom I’ve worked for years gave me a little challenge: a PDF with a hidden ciphertext. At first I had to use Excel to decipher the ciphertext, but later I wrote a small Python tool to help me.

The simple ciphers supported by this tool are XOR, ROT, Vigenère and subtract (I added that last one because it was used in a maldoc). You can use the man page (option -m) to learn more.

cipher-tool_V0_0_1.zip (https)
MD5: B7D44090A76F66D7194D0A0D890E2CEB
SHA256: 1E8E1F112595FC08C3C20A06D172C21DDE6375EC8651A8DE6EF57B938F3E67E8

Monday 21 November 2016

Update: base64dump.py Version 0.0.5

Filed under: My Software,Uncategorized — Didier Stevens @ 0:00

This new version supports different encodings besides base64 (but the name remains base64dump).

The new encodings are hexadecimal (hex), \u unicode (bu) and %u unicode (pu).

Here’s an example with escaped unicode in JavaScript (%u), namely a PDF with shellcode in JavaScript:

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The shellcode, escaped with %u, can be extracted with base64dump:

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There’s also a new option to do a string dump: -S

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And a last small update: this version also counts unique bytes, i.e. the number of different byte values found in the data.

base64dump_V0_0_5.zip (https)
MD5: 7AACFD3E34FEAAF41897F60FBC5279A3
SHA256: B4AB7B3A9D2947F08C6CC94F88CD825C9B2B63EE65AF7475E66BE9565EC4337A

Sunday 20 November 2016

Update: zipdump.py Version 0.0.4

Filed under: My Software,Update — Didier Stevens @ 0:00

A small update to zipdump: this version displays the ZIP comment (if present) and also counts unique bytes, i.e. the number of different byte values found in the data.

zipdump_v0_0_4.zip (https)
MD5: 64EE6575309654B6671554D0A4DA50E5
SHA256: C323C0580E95F87406A72A542A7FBF5DE39EBEF7CAFC970A7C428CA1E870F9CF

Saturday 19 November 2016

Update: byte_stats.py Version 0.0.4

Filed under: My Software,Update — Didier Stevens @ 0:00

A small update to byte-stats: this version also counts unique bytes, i.e. the number of different byte values found in the data.

byte-stats_V0_0_4.zip (https)
MD5: B53CE5444618DCA78C46C7F72E356D8D
SHA256: 81EFED375FF666BFFDDB82D094ECE17074182F5016FE3BFA4D1CA33DE838754C

Friday 18 November 2016

Update: shellcode2vba.py Version 0.5

Filed under: My Software,Shellcode,Update — Didier Stevens @ 0:00

shellcode2vba.py is a Python program to create VBA code to inject shellcode. This new version has 1 new option:

Option –suffix allows you to instruct the program to add a suffix to the VBA function names.

shellcode2vba_v0_5.zip (https)
MD5: BAD6684A6887F9E90FF755609B4CA2D5
SHA256: C403CD8196593F2ADD6BED40E9E7A14E49DB48909788DE8BB27A95D71E58A13A

Sunday 23 October 2016

Update: virustotal-search.py Version 0.1.4

Filed under: My Software,Update — Didier Stevens @ 0:00

This new version of virustotal-search.py accepts input from stdin.

virustotal-search_V0_1_4.zip (https)
MD5: 867D6272792965D11317BFB6308E20A9
SHA256: 8C033B3C46767590C54C191AEEDC0162B3B8CCDE0D7B75841A6552CA9DE76044

Saturday 22 October 2016

Update: cut-bytes.py Version 0.0.4

Filed under: My Software,Update — Didier Stevens @ 9:49

I added dumps to this new version of cut-bytes.py:

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cut-bytes_V0_0_4.zip (https)
MD5: A44D8BBE9BAB9309E732F8995CB5C7BB
SHA256: F95453DE1CC5855C320AB947D9AE354BE8E3ABFA52418C0CF623351A9DBF6344

Monday 17 October 2016

Update: oledump.py Version 0.0.25

Filed under: My Software,Update — Didier Stevens @ 0:00

This new version has a couple of new options (–decoderdir and –plugindir) and a bugfix.

oledump_V0_0_25.zip (https)
MD5: CED1602AEF505AE0388DB95414F9C00A
SHA256: 54510A54264E4EA3C4559545B5CE43A20D8AB290B4EDDA7B57983AD1396E29FC

Friday 14 October 2016

Analyzing Office Maldocs With Decoder.xls

Filed under: maldoc,Malware,My Software — Didier Stevens @ 13:27

There are Office maldocs out there with some complex payload decoding algorithms. Sometimes I don’t have the time to convert the decoding routines to Python, and then I will use the VBA interpreter in Excel. But I have to be careful not to execute the payload, just decode it. In the following video, I show how I do this.

Tools: oledump.py, decoder.xls

Sample: 2f918f49c3f926bb1538eaad6e8e6883

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